1. Field of the Invention
The present invention is directed to a friction clutch having wear compensation.
2. Description of the Related Art
Wear occurs in friction clutches over the duration of their operating life in the region of friction linings of a clutch disk of the friction clutch. The wear produces a change in the force characteristic of an energy accumulator if the wear is not compensated for, thereby changing the required actuating force over the life of the clutch. The change in required actuating force is especially apparent during manual actuation of the clutch. The occurring wear also requires that the clutch disks be replaced when the friction linings are almost completely worn out but before the linings are completely worn to maximize the life of the clutch lining and prevent damage which may occur when the linings are completely worn.
It is the object of the present invention to provide a friction clutch and a thrust plate assembly for a friction clutch in which the need to replace a clutch disk is detected early.
According to the present invention, the object is met through a friction clutch including a wear state indicating arrangement.
The wear state indicating arrangement supplies information to the user of the vehicle having this type of friction clutch regarding the status of wear of the clutch or whether or not the clutch disk has reached a replacement state in which it is are required to be replaced by a new clutch disk. The indication makes it possible to avoid operating the vehicle over a long period when the clutch disk is completely worn out, which could lead to damage to other components and, in particular, would result in that the required torque could no longer be transmitted via the clutch.
The friction clutch may, for example, comprise a housing and a pressure plate arranged in the housing and connected with the housing so as to be substantially fixed with respect to rotation relative to it and displaceable in the direction of an axis of rotation relative to the housing. The pressure plate has a friction surface region for contacting a counterfriction surface on a friction lining of a clutch disk or similar element. The wear state indicating arrangement is designed to indicate the wear occurring substantially in the region of friction linings of the clutch disk.
To gather information about the state of wear in a simple manner, the friction clutch according to the invention may comprise at least one element which is displaceable when wear occurs. In this embodiment, the wear state indicating arrangement is designed to indicate wear based on the displacement of the at least one element.
In an arrangement which is especially simple to build, the wear state indicating arrangement may comprise at least one indicating element which is arranged so as to be rotatable at the friction clutch. The at least one indicating element is arranged so that it is set in rotation by the displacement of the at least one element.
A wear state indicating arrangement of this kind continuously indicates the wear state of the clutch.
In one embodiment, the at least one element may comprise a first toothed area in a meshed engagement with a second toothed area provided at the at least one indicating element.
In another embodiment form, the at least one element may have at least one indicating mark which moves when the at least one element is displaced relative to at least one reference mark. Accordingly, the wear state indicating arrangement comprises at least one indicating mark and at least one reference mark. The relative position of the indicating mark and the reference mark indicates the wear state of the friction clutch so that it is possible to continuously track the wear state of a friction clutch and of the clutch disk.
In another embodiment form, the wear state indicating arrangement comprises at least one indicating member which is pretensioned or is pretensionable toward a wear indicating position. In this embodiment, the at least one indicating member moves corresponding to the displacement of the at least one element toward the wear indicating position.
The at least one indicating member may be held by the at least one element in a wear-free indicating position, i.e., a position which indicates that there is no wear, until the at least one element has been displaced into a predetermined position corresponding to when the friction linings are nearly fully worn. When the at least one element is displaced to the predetermined position, the at least one element releases the at least one indicating member and the at least one indicating member is allowed to move to the wear indicating position. In this type of wear state indicating arrangement, the transition of the at least one indicating member from the wear-free indicating position to the wear indicating position indicates that the clutch disk has now entered a wear state that may not yet be critical at the moment, but which requires replacement of the clutch disk as soon as possible.
In a simple embodiment, the at least one indicating member may be pretensioned or pretensionable by centrifugal force in the wear indicating position.
Further, the at least one indicating member may have a first contact area by which the at least one indicating member contacts the at least one element in the wear-free indication position and a second contact area by which the at least one indicating member contacts the at least one element after moving into the wear indicating position.
Since modern friction clutches often employ wear compensation adjustment devices that automatically compensate for occurring wear and that generally contain structural component parts which are displaced in a compulsory manner when wear occurs and when wear compensation is carried out, it is suggested according to another aspect of the present invention that the at least one element is at least a part of a wear compensating adjustment device via which wear is compensated. For example, the at least one element may comprise an adjusting ring which is essentially rotatable about the axis of rotation when wear occurs.
It is especially advantageous to indicate the wear state when using a friction clutch with a wear compensating adjustment device because it would not be known through a changing actuation force that the clutch has reached a critical state. That is, when a clutch comprises a wear compensation device, there is no change in actuation force as the wear progresses. Therefore, the actuation force provides no indication to the user even when the clutch has reached a critical state with respect to wear.
The clutch according to the invention may comprise an energy accumulator supported at a clutch housing on one side and at a pressure plate via the wear compensating adjustment device on the other side.
The present invention is further directed to a thrust plate assembly for a friction clutch according to the invention, wherein the wear state indicating arrangement according to the present invention is provided at the thrust plate assembly.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.